Aphex 1788A Premium Eight Chan Mic Pre - Manual (Page 41)

Page 40
MICROPHONE PREAMPLIFIER
Page 41
Instruction Manual
APPENDIX D
A word on impedance and interfacing adapt-
ers: If you are connecting between two line level
devices and they have different connectors (example:
1/4” phone to XLR or vice-versa), you do not need to
use an impedance matching transformer. With very
few exceptions you are strictly dealing with a differ-
ence in connector types and should only use hard-
wired adapters (or cables) for this situation.
APPENDIX D: Standard Cable Wiring
In relation to 1/4” phone jacks, you may see the terms
“TS” and “TRS” as abbreviations. Here is a what that
means: TS refers to the Tip-Sleeve or “mono” 2-
conductor type and TRS refers to Tip-Ring-Sleeve or
“stereo” 3 conductor type 1/4” phone connectors.
This applies to jacks (female connectors) and plugs
(male connectors).
Note: We recommend using only conventional
1/4” phone plugs with the Model 230 and with
all other audio equipment. Professional patch bay
cords using brass PJ055 telephone type plugs are
designed only for patch bays and will not make
proper contact with standard 1/4” phone jacks.
The following instructions show all the different ways
you will probably ever need to hook up your 230 as
well as any other equipment you may own. You will
see that connecting balanced outputs to balanced
inputs is ultimately simple and the same cable will
work for all flavors of output stages.
TABLE 1 - BALANCED & UNBALANCED CONNECTOR WIRING STAN-
3-Pin XLR 1/4” TRS Phone Standard Wiring Convention (Balanced)
Pin-1 Sleeve Ground/Shield (Earth, Screen)
Pin-2 Tip Positive (Signal, High, Hot)
Pin-3 Ring Negative (Signal Reference, Return, Low, Common)
1/4” TS Phone RCA Standard Wiring Convention (Unbalanced)
Tip Center Pin Positive (Signal)
Sleeve Shell Ground/Shield (Signal Reference/Return)
Connecting a balanced output to an unbalanced
input requires a little more knowledge and care.
You should refer to your equipment manuals and
determine the type of balanced output stage that is
provided, then use the correct “transition cable” as
depicted in this section. Improper transition cables
can cause crosstalk, hum, and distortion problems
within your system.
TYPES OF BALANCED OUTPUTS
Believe it or not, there are at least 5 types of balanced
output stages in use today. They may be placed
into two main classes: transformer balanced, and
transformerless balanced, usually called “active bal-
anced”. Transformer balanced outputs are becoming
outdated because of their high cost and their sonic
limitations. However, they can still be found on a lot
of older equipment.
Within the transformerless class, there are several
types of circuits that are used by different manufac-
turers. These different types of output circuits all look
just about alike to any balanced line, but they act dif-
ferently when driving an unbalanced line. You need
to observe the proper cable wiring for each type of
output circuit. We strongly recommend that you refer
to your various equipment manuals to find out what
is used in each case before hooking up to unbalanced
lines.
When connecting a balanced output to a balanced
input, however, you don’t need to know what kind
of balanced output you are dealing with. Simply
treat it generically.